1. Field of the Invention
The present invention relates to a secondary battery pack having a residual capacity display function, a portable electronic device having the residual capacity display function of the secondary battery, and a method for displaying residual capacity of the secondary battery.
2. Description of the Related Art
Conventionally, two-color light emitting diodes (LEDs) are generally used for displaying residual capacity of a secondary battery. For example, neither of the LEDs lights up when the secondary battery is not attached to a charger, an orange LED lights up during the charge thereof, and a green LED lights up in a full charge state. When a single-color LED is used, the LED does not light up when the secondary battery is not attached to the charger, flashes during the charge, and lights up in the full charge state to attain a same purpose.
When a user can know the residual capacity of the secondary battery in more detail, he/she can estimate an operating time of the device, and further an exchange timing of the secondary battery. Therefore, a portable electronic device with a built-in secondary battery is required to more precisely display the residual capacity of the secondary battery. For this purpose, a method is employed in which a large number of LEDs are used and number of lighting LEDs is increased or decreased depending on the residual capacity of the secondary battery.
The portable electronic device with the secondary battery can detect the residual capacity thereof and display it in detail using a large number of LEDs as discussed above. A secondary battery pack, however, singly, cannot precisely display the residual capacity, because it displays the residual capacity with a single LED as discussed above. When the user attaches the secondary battery pack to the portable electronic device to start up the device every time he/she intends to know the residual capacity in detail, a longer time is inconveniently spent for the charge.
As discussed above, a conventional residual-capacity displaying method using a single LED has a problem that the progress of the charge cannot be precisely recognized. When a plurality of LEDs are provided for indicating a charge state in more detail, a cost increases and larger power is consumed in the LEDs for displaying the residual capacity.
The present invention addresses the conventional problems discussed above. A secondary battery pack in accordance with the present invention comprises a secondary battery for supplying power to a portable electronic device, a controller for calculating residual capacity of the secondary battery, and a display unit for displaying the residual capacity. The display unit has at least two kinds of display states, and indicates the residual capacity of the secondary battery using a ratio between respective display times of the two kinds of display states.
A portable information device in accordance with the present invention comprises a secondary battery for supplying power to a portable electronic device, a controller for calculating residual capacity of the secondary battery, and a display unit for displaying the residual capacity. The display unit has at least two kinds of display states, and indicates the residual capacity of the secondary battery using a ratio between respective display times of the two kinds of display states.
A residual capacity displaying method of the secondary battery in accordance with the present invention comprises steps of calculating the residual capacity of the secondary battery, and displaying the residual capacity of the secondary battery using a ratio between respective display times of a first display element and a second display element that are different from each other in color.